Made a marshmallow mix but it isn't whipping

If that is the process you used, then that's why it failed. The gelatin should have been in the bowl to start with, and you gradually pour in the hot syrup while you whip the mixture. Every marshmallow recipe I've ever seen or used calls for you to gradually beat the syrup into the gelatin- rather than the way you describe. If the syrup cools before the gelatin melts and traps air, and gets set by the heat, you don't get marshmallows. You will have to toss this mixture, because it will never work, and give it a second shot. Soften your gelatin in a deep bowl, big enough for the mixture to expand in size. Then gradually pour in the hot syrup into the gelatin while you are mixing on about medium speed. Once the gelatin has melted again, which it should do pretty quickly, turn your speed to as high as it will go and beat until it forms the marshmallow cream. It may take 30 minutes of beating or more.

When you make marshmallows, it's usual to pour the hot sugar syrup into the gelatine mixture with your stand mixture running. Your sugar syrup will need to be at least 240F before it hits the mixture as well. If it is not at the correct temperature, it will not be able to set the gelatine so it can hold air bubbles. I notice a few things from your photo which could make trouble as well. Your bowl is pretty small for holding the amount of mixture that it should be expanding into. You also have a hand mixer. It may be your mixer is not powerful enough to whip enough air into the mixture before it cools too much. And with a hand mixer, it can take as long as 45 minutes of whipping to create the foam you need. If you post the recipe you are using, we may be able to give you more help as well.